1. Field of the Invention
The field of art to which this invention pertains is dibenzofuran tetracarboxylic acid dianhydrides and polymers derived therefrom including polymers formed from the reaction of a diamine and the dianhydride.
2. Description of the Prior Art
Relevant art which in part describes the tetrazotization of diaminopolymethylbiphenyls is described in one of the general paper sessions presented before the Division of Petroleum Chemistry, Inc. of the American Chemical Society at the Boston meeting of April 9-14, 1972. In particular, a paper entitled "Cyclizations With Dinitropolymethylbiphenyls and Diaminopolymethylbiphenyls" by Imre Puskas, Ellis K. Fields and E. M. Banas, pages B56-B63 of the general paper describes a method for the production of polymethyl substituted dibenzofurans.